Method for forming sheet metal corner members



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METHOD FOR FORMING SHEET METAL CORNER MEMBERS Filed April 15, 1966 Sheet 1 of 5 April 1969 R. E. ROPER 3,440,711

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METHOD FOR FORMING SHEET METAL CORNER MEMBERS v Filed April 15, 1966 Sheet 5 of 5 11V KENT 0R. HALPH E. RoPER United States 3,440,711 METHOD FOR FORMING SHEET METAL CORNER MEMBERS Ralph E. Roper, Indianapolis, Ind., assignor to Wallace Expanding Machines, Inc., Indianapolis, Ind., a corporation of Indiana Filed Apr. 15, 1966, Ser. No. 542,896 Int. Cl. B23k 31/02 US. Cl. 29-480 4 Claims ABSTRACT OF THE DISCLOSURE A process and apparatus for forming sheet metal members into corners whereby the sheet metal is cut to define edge portions, the edge portions are folded into engagement and welded together and the thus formed corner is finished by squeezing and plastic deformation between dies.

The present invention relates to method and apparatus forming the corners of sheet metal panels such as refrigerator doors, freezer doors and the like.

One presently used method of fabricating panels from sheet met-a1 includes notching. the corners of a sheet metal blank and making a first inner bend at right angles to the center section. Next a second bend or fold is made a dis tance outwardly from the first bend corresponding to the desired panel thickness. The second fold thus forms a flange substantially parallel to the center section of the blank. The corner notches of the blanks are so shaped as to provide an abutting joint along each corner of the folded panel and a mitered. joint joining the side flanges and end flanges. The joints are then welded, brazed or fuzed and subsequently hand worked by grinding and other operations in preparation for painting, plating, or other final decorative or protective finish. One disadvantage of the above described method of fabrication is the time consumed in hand finishing the corners of each panel and the unavoidable non-uniformity of contour resulting therefrom.

Consequently, an important object of the present in vention is to provide improved method and apparatus for forming the corners in sheet. metal panels.

A further object of the present invention is to provide method and apparatus for forming the corners of sheet metal panels which compared to presently known pro-= cedures drastically reduces man hours of finishing labor.

A further object of the present invention is to provide method and apparatus forforming the corners of sheet metal panels which produfces formed corners accurately and uniform in contouri 1 Related advantages of "the invention are that :by eliminating skilled labor to complete the corner forming operation, an automated assembly line for door forming is made possible, expensive labor costs are avoided, and re= jected parts due to poor workmanship are substantially reduced.

Other related objects and advantages will become apparent as the description proceeds.

One embodiment of the method of the present invention comprises the steps of bending a notched sheet metal blank to form a rectangular panel having abutting edges forming the corners, clamping the abutting edges together, fuzing the abutting edges to a solid metal corner, and then forming the fuzed corner between a pair of dies.

One embodiment of the apparatus of the present invention might include a welding jig with a movable clarnp element for holding the edges of a door corner seam in abutting relationship, a pair of welding guns disposed at right angles to one another and arranged to f-uze the seams while held by said jig into a solid metal corner, a stationary punch element supporting the interior surfaces of a door corner and a movable die aligned therewith, said punch and die being arranged to compress the fuzed seam and adjacent metal into a smoothly contoured finished form ready for painting or plating.

The full nature of the invention will be understood from the accompanying drawings and the following description and claims.

FIG. 1 is a perspective view of corner fuzing apparatus forming a part of the present invention.

FIG. 2 is a vertical section taken generally along the line 22 of FIG. 1 and viewed in the direction of the arrows.

FIG. 3 is an enlarged fragmentary section similar to FIG. 2 through clamping mechanism for-ming a part of the corner fuzing apparatus of FIG. 1, the parts being shown in a position corresponding to the completion of the fuzing operation.

FIG. 4 is an enlarged fragmentary front elevation of the apparatus of FIG. 1.

FIGS. 5, 6 and 7 are perspective serial views of the workpiece generally illustrating the unclamped- 'clamped and fuzed appearance, respectively of a panel corner.

FIG; 6A is a section taken along the line 6A'6A of FIG. 6 in the direction of the arrows.

FIG. 8 is a perspective view of punch and die apparatus forming a part of the present invention.

FIG. 9 is an enlarged fragmentary vertical section taken generally along the line 9-9 of FIG. 8 andviewed in; the direction of the arrows but showing the parts in a different operating position than in FIG. 8.

FIG. 10 is a horizontal section taken along the line 10-10 of FIG. 9 and viewed in the direction of the arrows.

For the purposes of promoting an understanding of the principles of the invention, reference will now be inade to the embodiment illustrated in the drawing and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scopeof the invention is thereby intended, such alterations and further modifications in the illustrated device, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates.

Referring now to the drawings and particularly to FIGS. 1 7, there is shown fuzing apparatus 10, consisting of a frame 11 mounted upon a base 12. A plate 15 is fixedly mounted to the front face of the frame and is located at the upper portion thereof. The plate 15 has alfixed thereto clamping means generally referred to by numeral 16. Clamping means 16 consists of a movable clamp member 17, mounted for vertical reciprocation on plate 15, and stationary clamp members or halves 21 and 22 fixedly mounted to to plate 15 in alignment with clamp member 17. Clamp halves 21 and 22 have recesses 25 and 26, respectively, formed therein. The recesses 25 and 26 are defined by forwardly facing surfaces 25A and 26A and downwardly facing surfaces 25B and 26B. The surfaces 25B and 26B have a transverse dimension corresponding to the thickness of a panel to be fuzed and extend at a angle to one another.

The upper end of movable clamp member 17 includes two surfaces 27A and 27B which form a 90 angle relative to one another and meet at an apex or junction 27. The apex 27 is formed by an insert 270 made of copper or some other metal incompatible with the metal of the workpiece to prevent fuzing of the workpiece to the member 27C. A door panel 24, indicated by broken lines in FIG. 1 and in solid lines in FIG. 3, is placed on movable clamp member 17 so that the panel is supported from one corner by the surfaces 27A and 27B of the clamp member 17. The thickness of clamp member 17 corresponds to the inside dimension of the door panel. In other Words, the thickness of the member 17 is equal to or slightly less than the distance from the inner face 24A of the panel front 24B to the inner face 24C of the parallel back flange 24D.

Guide tracks 28 and 29 are fixedly mounted to plate and are recessed at 31 and 32 (FIG. 4), so as to slidably receive tongues 35 and 36 of movable clamp 17, thereby guiding clamp member 17 as it moves upwardly into clamping registry with clamp halves 21 and 22. Fixed to the clamp member 17 are wings 33 which function to support the panel 24 so that it does not swing on the clamp member during movement thereof. One end of a lever arm 37 is pivotally; secured to the inside face of movable clamp 17 at the lower portion thereof. Lever arms 38 and 39.,are pivotally secured to bearing block 42 which is fixed to plate 15. The opposite ends of levers 37, 38 and 39 are pivotally secured to a clevis 45 fixed to the piston 46 .of an air cylinder 47. Cylinder 47 is pivotally mounted at 48 to frame 11.

The clamping means thus far described receives one corner of a panel which has been preformed to the condition illustrated in FIG. 5. This preforming can be accom= plished by any suitable folding or bending apparatus to form inner terminal portions 48 and outer terminal portions 49. It will be noted that the edges 51 and 52 of the terminal portions 48 and 49 are to some degree separated and/or out of alignment. Extension of piston 46 leftwardly, as viewed in FIG. 2, causes clamp member 17 to move upwardly into clamping engagement with clamp halves 21 and 22. Referring to FIGS. 6 and 6A, a panel corner pressed between clamp member 17 and clamp halves 21 and 22 will have terminal portions 48 partially overlapping and firmly pressed together and terminal portions 49 aligned and abutting and firmly pressed together. With the panel in this position, the contacting edges 51 will be exposed between clamp halves 21 and 22 at 55 (FIG. 4). and the contacting edges 52 will be exposed between clamp halves 21 and 22 at 56 (FIG. 4).

Fuzing or welding guns 57 and 58, having are tips or electrodes 59 and 60, respectively, are fixedly mounted to moveable plates 62 and 63 in such a manner that their are tips 59 and 60 are closely adjacent the apices 51A and 52A (FIGS. 3 and 6) of the clamped door panel corner. The fuzing guns place no new metal in the welds which they produce. The fuzing guns are commercially available items and might be. for example, Heliarc Guns Linde HW 13 manufactured by Union Carbide of Indianapolis, Ind. (Linde Division). The guns are also each provided with inert gas outlets which operate to cover the weld with inert gas when the gun is in operation. The welding circuit is made through the electrodes 59 and 60 to the copper member 27C.

Plates 62 and 63 are guided in trackways 65 and 66 and trackways 67 and 68, respectively, the trackways being mounted to side plates 70 and 71 which are fixedly secured to frame 11. Each plate 62 and 63 has fixedly mounted thereto, racks 72 and 73, respectively, which are engaged by pinion gears 76 and 77. Pinion gears 76 are fixed to shaft 78 and pinion gears 77 are fixed to shaft 79. Electric clutches 81 and 82 connect shafts 78 and 79 to synchronized electric motors 85 and 86 through variable gear reducers 87 and 88, respectively. The trackways 65 and 66 extend parallel to the top surface 170 (FIG. 3) of the clamp member 17. Trackways 67 and 68 extend parallel to the rear surface 17D (FIG. 3) of the clamp member 17. The fuzing guns 57 and 58 are movable in the trackways to and from the above mentioned initial position by the operation of the motors 85 and 86. As the fuzing guns 57 and 58 are moved from the dotted line to the full line position as illustrated in FIG. 3, the electrodes 59 and 60 will move along the edges 51 and 52, respectively, of the door panel corner being held in clamped position by the clamp members 17, 21 and 22.

After the door panel 24 has been hooked on the clamp member 17, the cylinder 47 is operable to raise clamp member 17 to the dotted line position of FIG. 4 at which time clutches 81 and 82 are energized and simultaneously high potential current provided to electrodes 59 and 60. Also the guns 57 and 58 begin to emit inert gas. Energizing of clutches 81 and 82 couples shafts 78 and 79 to the continuously rotating output shafts of reducers 87 and 88 causing pinion gears 76 and 77 to drive plates 62 and 63 and their associated welding guns 57 and 58 rightwardly and downwardly, respectively, as viewed in FIG. 3. The arc between tips 59 and 60 and edges 51 and 52 fuzes the edges (FIG. 6) to form a solid metal corner as indicated at 128 and 129 in FIG. 7.

At the end of the fuzing cycle the fuzing guns are positioned as illustrated in solid lines in FIG. 3. When the guns reach these positions, the current to the electrodes 59 and 60 is terminated and deenergizing of clutches 81 and 82 takes place as well as the turning off of the inert gas flow. At this time the clamp member 17 is lowered by retraction of piston 46 of air cylinder 47. Also, at this time fuzing gun 57 is returned to the dotted line position of FIG. 3 by air cylinder 91. The air cylinder 91 is mounted on the plate 62 and has its piston rod secured to the cross plate 93 fixed to the side plates 70. The fuzing gun 58 is returned to the dotted line position of FIG. .3 simultaneously with the return movement of fuzing gun 57 by a pair of air cylinders 92 acting through L-shaped brackets 95 fixed to plate 63.

Referring now to FIGS. 8, 9 and 10, the forming apparatus of this invention includes a frame which mounts a punch and die generally referred to by numeral 101. An elongated mounting block 102 has bolted thereto a punch member 103 which is provided with a pointed upper end including two surfaces 103A and 103B forming a 90 angle relative to one another and meeting at an apex or junction 103C. Thus the configuration of the punch member 103 is similar to the configuration of the clamp member 17.

A die block, generally referred to by numeral 104, is composed of a main body portion 105 having a V- shape recess 106 machined in its lower portion. The rear face 1063 of recess 106 is partially defined by a hardened steel insert 106A for a purpose described below. The rear face 105A of body portion 105 has fixedly secured thereto a guide plate 107 which overlies a necked down portion 105B of body 105 thus defining oppositely opening slots 108. A hearing plate 109 is fixed to the front face 110 of mounting block 102.

Guide track members 111 of U-shaped cross section are bolted to the sides of mounting block 102 so that one leg 111A of the U-shape projects into slots 108 and the other leg of the U-shape is received in slots 112 formed in the sides of block 102.

One end 115 of an L-shaped lever 116 is pivotally secured to the upper end of die block 105 by pin 117. The other end 118 of the L-shaped lever 116 is pivotally mounted by pin 119 to the clevis 120 of air cylinder 121. Air cylinder 121 is pivotally mounted to frame 100 by pins 121A. A pair of links 122 each have one end pivotally mounted to the elbow of L-shaped lever 116 by pin 125 and the other end pivotally secured to mounting block 102 by pin 126. A stop block 127 is bolted to mounting block 102 in a position such as to limit or prevent the travel of lever arm 116 rightwardly past the solid line position illustrated in FIG. 9.

In operation, a door panel received from the fuzing apparatus with all its comers in the form shown in FIG. 7 is placed with one corner overlying punch member 103. The fuzed seam 128 forming the corner edge perpendicular to the front of the panel is rough and un even as indicated in FIG. 7. The apex of die cavity 106 corresponding to this corner edge is shaped with a smooth corner configuration which smooths out the uneven fuzed seam 128 by plastic deformation thereof when the panel corner is formed between the punch and die cavity. Seam 129 joining the flanges of the rear face of the door panel is not exposed in the finished product inasmuch as the flanges serve as a mounting face-for a separate panel formingthe interior face of the door. Insert 106A in the rear face of cavity 106 therefore functions to shear the uneven portions of the seam 129 flush with the adjacent flange surfaces 129A and 1293 (FIG. 7).

Actuation of die member 104 is achieved by retraction and extension of the piston 135 of air cylinder 121. The extendedipiston open die position-is shown in FIG. 8 and in dotted outline in FIG. 9. The solid line position of FIG. 9 is, of course, the retracted piston closed die forming 'position of the apparatus. When the piston 135 is retracted, the lever arm 116 engages stop block 127 to stop the movement of the female forming member 106' at a predetermined spacing from the male forming mem her 103. This spacing is such as to effect the desired external forming of the comer of the panel 'at the seam 128.

A cycle start switch 129, when depressed, overrides cycle stop switch 130 activated by arm v131 fixed to die block 104. Arm 131, moving downwardly with die block 104, allotvs switch 130 to close holding the pneumatic circuit (not shown) in operative condition. A pressure switch (not shown) in the pneumatic circuit reverses the air pressure through conventional valving means to return the die block to its up position. Arm 131 engages the activating lever of switch 130 which in turn operates the air supply valve to off position. A jogging switch 132 is provided to bypass the cycling circuit enabling inter mittent lowering and raising of dieblock 104 necessary to the accomplishment of die set up. Since the electrical and pneumatic circuit of the apparatus forms no part of the present invention, it will not be described further herein.

It will be evident from the above description that the present invention provides a method and apparatus for forming and finishing the corners of sheet metal panels which substantially reduces labor cost. [It should be understood that after the welding step of this invention, the forming step in the apparatus of FIGS. 8, 9 and 10 finishes the weld to an extent making unnecessary further finishing. It will also be evident that the method and ap-= paratus of the present invention provide a much greater accuracy and uniformity than that possible by hand finish While the invention has been illustrated and described in detail in the drawings and foregoing description, the

edge portions, said adjacent edge portions each including an inner terminal portion and an outer terminal portion, folding theedge portions to a position wherein they en gage one another and define a corner, said folding caus ing said inner terminal portions to be substantially per pendicular to said blank and to engage one another and said outer terminal portions to be substantially parallel to said blank and to engage one another, welding the edge portions together to form the rough configuration desired for the corner, positioning said corner between a pair of rigid dies, moving said dies toward one another with sulficient force to squeeze and plastically deform said corner into the finished configuration desired for said corner.

2. The process of claim 1 wherein said deforming is effected between a male die within said corner and a female die located externally of said corner, said welding being accomplished between said outer terminal portions as well as between said inner terminal portions, said process further including the step of shearing oif the external surface of said outer terminal portions and a portion of the weld between said outer terminal portions.

3. The process of claim 2 additionally comprising the step carried out simultaneously with said welding of clamping the sheet metal blank and folded edge portions with said inner terminal portions partially overlapping one another and extending at right angles to one another and with said outer terminal portions abutting one another and in alignment with one another, said welding adding no additional metal to the corner and using inert gas to protect the weld.

4. The process of claim 1 additionally comprising the step carried out simultaneously with said welding of clamping the sheet metal blank and folded edge portions with said inner terminal portions partially overlapping one another and extending at right angles to one another and with said outer terminal portions abutting one another and in alignment with one another.

References Cited UNITED STATES PATENTS 1,934,765 11/1933 Iulien 1... 52- 656 X 2,025,922 12/1935 Weinrich 29480 X 2,139,423 12/ 1938 Scheeler 52-656 X 2,219,595 10/ 1940 Lang 29-476 2,280,150 4/1942 Hasse et al u 29-493 X 3,139,161 6/1964 Simon 5265 8 3,163,390 1/ 1965 Stanley 29476 X 3,264,730 8/1966 Roper 29476 X 3,305,998 2/1967 'Deisenroth 29-476 X JOHN F. CAMPBELL, Primary Examiner.

I. L. CLI'NE, Assistant Examiner.

US. Cl. X.R. 29--494; 219--l2l 

